Reduction Swellability

STUDY ON THE IMPROVEMENTS OF REDUCTION SWELLABILITY AND LOW TEMPERATURE REDUCTION DISINTEGRATION OF VANADIUM-TITANIUM MAGNETITE OXIDIZED PELLETS... 

Key Words Vanadium-Titanium Magnetite, Reduction Swellability, Low Temperature Reduction Disintegration, Oxidized Pellets... 

RSI of pellets without pretreating is 24.75%, crack is much, and reduction swellability is serious in Table III and Figure 1. RSI of roasted pellets pretreated is decreased from 24.75% to 19.85% and 20.01%, and reduction swellability is decreased obviously. The integrity of pellets pretreated after reduction is improved and RDI+a.smm is from 58.82% to 68.79% and 65.08%. But pellets of HPRG are disintegrated more seriously than pellets without pretreating and RDI of damp milling is improved. 

The grafting reaction depends upon the degree of substitution as well as the kind of pulp used. Introducing acetyl groups in the cellulose chains (high substitution) causes a large reduction of its swellability, which reduces the diffusion of the reactants. Thus, acetylation lowers the graftability of the cellulose. 

As an example, consider the use of PVPy as a solid poison in the study of poly(noibomene)-supported Pd-NHC complexes in Suzuki reactions of aryl chlorides and phenylboroiuc acid in DMF (23). This polymeric piecatalyst is soluble under some of the reaction conditions employed and thus it presents a different situation from the work using porous, insoluble oxide catalysts (12-13). Like past studies, addition of PVPy resulted in a reduction in reaction yield. However, the reaction solution was observed to become noticeably more viscous, and the cause of the reduced yield - catalyst poisoning vs. transport limitations on reaction kinetics - was not immediately obvious. The authors thus added a non-functionalized poly(styrene), which should only affect the reaction via non-specific physical means (e.g., increase in solution viscosity, etc.), and also observed a decrease in reaction yield. They thus demonstrated a drawback in the use of the potentially swellable PVPy with soluble (23) or swellable (20) catalysts in certain solvents. 

Some patents or applications employ prior art AST compositions to obtain use features providing enhanced performance or utility. Synergistic thickening is observed, for example, when associative ASTs are combined with various other components, for example, with surfactants (82), with water-swellable clay minerals (111), or with nonionic associative thickeners 112, 113), Witiak and Dupre (114) disclose utility of AST latices in acidic media. This utility is accomplished by neutralization to a pH above 6.5 followed by reduction to some lower pH in the presence of surfactant. In spite of the low pH, the surfactant prevented coagulation on reacidification. 

The reduction of scrub resistance is the main disadvantage of HEUR/ hydrophobically modified alkali-swellable latex thickener systems 18, 19). Hydrophobically modified alkali-swellable latex-thickened paints often show increased water and alkali sensitivity, reduced wet and dry adhesion, and lower scrub resistance than similar cellulosic-thickened paints. 

Treatment of n-type polyacetylene with any of a variety of alkyl halides in THF typically leads to a dramatic swelling of the film and the formation of an orange-red, soluble fraction. The amount of alkylation of the insoluble but swellable films corresponds to ga- 0.9-1.3 alkyl groups per 10 CH units. Studies of the amount of alkylation of the polyacetylene and the amount of reduction products (R-H and R-R) formed as a function of alkyl halide type leads us to conclude that the mechanism involves initial electron transfer (perhaps more appropriately an electron shift) to R-X as shown in Scheme I. 

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